Optical connector with reduced mechanical-alignment sensitivity

ABSTRACT

An optical connector is described. This optical connector spatially segregates optical coupling between an optical fiber and an optical component, which relaxes the associated mechanical-alignment requirements. In particular, the optical connector includes an optical spreader component disposed on a substrate. This optical spreader component is optically coupled to the optical fiber at a first coupling region, and is configured to optically couple to the optical component at a second coupling region that is at a different location on the substrate than the first coupling region. Moreover, the first coupling region and the second coupling region are optically coupled by an optical waveguide.

BACKGROUND

1. Field

The present disclosure relates to an optical connector for couplingtogether optical components. More specifically, the present disclosurerelates to an optical connector for coupling together optical componentswith reduced mechanical-alignment sensitivity.

2. Related Art

While optical communication potentially offers higher performance thanelectrical communication, in many applications this advantage isoutweighed by higher costs. In particular, many optical systems havehigher manufacturing, installation, and maintenance costs. For example,optical connectors, which are used to optically couple systemscomponents, are often a major contributor to the overall cost of opticalsystems.

One reason for this is the need to establish and maintain tightmechanical alignment between optical connectors and associated opticalcomponents. Without such tight mechanical alignment, the opticalconnectors will reflect optical signals (instead of communicating them),thereby reducing the efficiency of the optical connector and, thus, theperformance of the optical systems. For example, carrier wavelengths inmany optical systems are on the order of 1 μm, and optical reflectionscan occur in optical connectors even if there is mechanical misalignmentof a quarter of a carrier wavelength. Thus, the mechanical alignmentrequirements in optical connectors can be less than 1 μm.

Some existing optical connectors address this design requirement usingprecision molded and polished components, as well as with mechanicalstrain-relief connectors. While these techniques facilitate precisemechanical alignment, the resulting optical connector is often large andexpensive.

Other existing optical connectors amortize the size and cost of anoptical connector across a parallel set of optical fibers, which areoften referred to as an ‘optical ribbon cable.’ For example, an opticalribbon cable may include twelve parallel optical fibers in aone-by-twelve arrangement. However, it is often difficult to furtherincrease the number of optical fibers in an optical ribbon cable (forexample, to multiple rows or more than twelve parallel optical fibers)while maintaining the required mechanical alignment.

Hence, what is needed is an optical connector without theabove-described problems.

SUMMARY

One embodiment of the present disclosure provides an optical connectorthat includes an optical fiber and an optical spreader component, whichis disposed on a substrate. This optical spreader component spatiallysegregates optical coupling between the optical fiber and an opticalcomponent. Moreover, the optical spreader component includes: a firstcoupling region that is optically coupled to the optical fiber; anoptical waveguide that is optically coupled to the first couplingregion; and a second coupling region that is optically coupled to theoptical waveguide, and which is configured to optically couple to theoptical component. Note that a location of the second coupling region isdifferent than a location of the first coupling region.

In some embodiments, the optical component includes: an optical source,an optical modulator, an optical detector, an optical fiber, and/oranother instance of the optical connector, which includes anotheroptical spreader component that is disposed on another substrate. Forexample, the second coupling region in the optical connector may beoptically coupled to a third coupling region in the other instance ofthe optical connector via optical proximity communication (such as via aspherical optical ball). However, in some embodiments the opticalcomponent is also disposed on the same substrate as the opticalconnector.

Because the coupling between the optical fiber and the optical spreadercomponent may be sensitive to mechanical alignment, the mechanicalcoupling between the optical fiber and the optical spreader componentmay be rigid. However, the optical coupling between the optical spreadercomponent and the optical component may be less sensitive to mechanicalalignment. Consequently, the optical spreader component may beconfigured to re-matably mechanically and/or optically couple to theoptical component. Furthermore, a mechanical alignment tolerance ofoptical coupling between the optical connector and the optical componentmay be larger than a carrier wavelength of an optical signal conveyedvia the optical fiber.

In some embodiments, the first coupling region includes an opticalcoupling component (such as a diffraction grating) that opticallycouples an optical signal from the optical fiber to the opticalwaveguide.

Note that the optical spreader component may be a passive device.

Furthermore, the optical spreader component may include routing from afirst group of coupling regions, which includes the first couplingregion, to second group of coupling regions, which includes the secondcoupling region.

In some embodiments, the optical spreader component includes componentsand functionality that facilitate processing and/or communication ofoptical signals, including: a wavelength-selective multiplexer, awavelength-selective de-multiplexer, optical switching of opticalsignals, an optical monitor, active optical amplitude equalization,and/or optical gain.

Another embodiment provides a system that includes the opticalconnector.

Another embodiment provides a method for spatially segregating opticalcoupling between the optical fiber and the optical component using theoptical connector. During this method, the first coupling region in theoptical spreader component in the optical connector receives the opticalsignal from the optical fiber. Then, the first coupling region opticallycouples the optical signal to the second coupling region in the opticalspreader component via the optical waveguide in the optical spreadercomponent. Next, the second coupling region optically couples theoptical signal to the optical component.

BRIEF DESCRIPTION OF THE FIGURES

FIG. 1A is a block diagram illustrating an optical connector and opticalcomponents in accordance with an embodiment of the present disclosure.

FIG. 1B is a block diagram illustrating overlap of the optical connectorand the optical components of FIG. 1A in accordance with an embodimentof the present disclosure.

FIG. 2A is a block diagram illustrating two instances of the opticalconnector of FIG. 1A in accordance with an embodiment of the presentdisclosure.

FIG. 2B is a block diagram illustrating overlap of the two instances ofthe optical connector in FIG. 2A in accordance with an embodiment of thepresent disclosure.

FIG. 2C is a block diagram illustrating overlap of the two instances ofthe optical connector in FIG. 2A in accordance with an embodiment of thepresent disclosure.

FIG. 3 is a flow chart illustrating a process for spatially segregatingoptical coupling between the optical fiber and the optical componentusing the optical connector of FIG. 1A in accordance with an embodimentof the present disclosure.

FIG. 4 is a block diagram illustrating a computer system that includesthe optical connector of FIG. 1A in accordance with an embodiment of thepresent disclosure.

Note that like reference numerals refer to corresponding partsthroughout the drawings. Moreover, multiple instances of the same partare designated by a common prefix separated from an instance number by adash.

DETAILED DESCRIPTION

The following description is presented to enable any person skilled inthe art to make and use the disclosure, and is provided in the contextof a particular application and its requirements. Various modificationsto the disclosed embodiments will be readily apparent to those skilledin the art, and the general principles defined herein may be applied toother embodiments and applications without departing from the spirit andscope of the present disclosure. Thus, the present disclosure is notintended to be limited to the embodiments shown, but is to be accordedthe widest scope consistent with the principles and features disclosedherein.

Embodiments of an optical connector, a system (such as a computersystem) that includes the optical connector, and a method for spatiallysegregating optical coupling are described. This optical connectorspatially segregates optical coupling between an optical fiber and anoptical component, which relaxes the associated mechanical-alignmentrequirements. In particular, the optical connector includes an opticalspreader component disposed on a substrate. This optical spreadercomponent is optically coupled to the optical fiber at a first couplingregion, and is configured to optically couple to the optical componentat a second coupling region that is at a different location on thesubstrate than the first coupling region. Moreover, the first couplingregion and the second coupling region are optically coupled by anoptical waveguide.

By spatially segregating the optical coupling between the optical fiberand the optical component, and by reducing the mechanical-alignmentrequirements, this optical connector can improve optical-system cost,performance and reliability. For example, the mechanical alignmentrequirements can be increased to on the order of 10 μm for an opticalsignal with a carrier wavelength of 1 μm, which allows the manufacturingand assembly cost of the optical connector to be significantly reducedrelative to existing optical connectors.

We now describe embodiments of an optical connector. As notedpreviously, it can be very difficult to achieve and maintain tightmechanical alignment, especially in optical connectors that directlycouple one or more optical fibers to one or more optical components,such as planar optical devices and/or other optical fibers. This isbecause small gaps or other mechanical misalignments between an opticalfiber and its coupling target can significantly attenuate opticalcoupling by increasing optical reflections. In the discussion thatfollows, the sensitivity of an optical connector to mechanicalmisalignment is significantly reduced (e.g. by an order of magnitude ormore).

FIG. 1A presents a block diagram illustrating an optical connector 110-1and optical components 118. Optical connector 110-1 includes opticalfibers 112 and an optical spreader component 114-1, which is disposed ona substrate 116-1. For example, substrate 116-1 may be silicon orsilicon-on-insulator (SOI). Optical spreader component 114-1 mayspatially segregate optical coupling between optical fibers 112 andoptical components 118. Moreover, optical spreader component 114-1 mayinclude: one or more coupling regions 120 that are optically coupled tooptical fibers 112 (and which are arranged in a two-by-two array);optical waveguides 122 that are optically coupled to coupling regions120; and coupling regions 124 that are optically coupled to opticalwaveguides 122, and which are configured to optically couple to opticalcomponents 118. Note that coupling regions 120 and 124 are at differentlocations on substrate 116-1 (i.e., they are spatially segregated).

Optical connector 110-1 may be optically coupled to optical components118 at coupling regions 124. FIG. 1B presents a block diagramillustrating overlap of optical connector 110-1 and optical components118 when they are optically coupled. In some embodiments, some or all ofoptical components 118 are disposed on substrate 116-1 or anothersubstrate. Thus, optical connector 110-1 may facilitate intra- orinter-chip optical communication. Furthermore, optical and/or mechanicalcoupling between optical components 118 and optical connector 110-1 canbe fixed (such as when optical components 118 are disposed on substrate116-1). However, as described further below, in other embodimentsoptical connector 110-1 facilitates re-matable optical and/or mechanicalcoupling to optical components 118.

Optical components 118 may include a wide variety of devices, including:an optical source (such as a laser), an optical detector, an opticalmodulator (such as a ring resonator), an optical fiber, and/or anoptical component that couples an optical signal into any of thesedevices. In embodiments where optical components 118 are disposed on asubstrate (such as substrate 116-1 or the other substrate), they may beincluded in a planar array of optical devices on: a package, chip,and/or board. For example, the planar array of devices may be includedon: a silicon photonics chip, a silicon optical bench, and/or an opticalwafer board.

In some embodiments, one or more of coupling regions 120 includes anoptical coupling component (such as a diffraction grating or a mirror)that optically couples optical signals from optical fibers 112 tooptical waveguides 122. For example, if substrate 116-1 is silicon, amirror may be fabricated along the 54° cleavage plane. Furthermore, adiffraction grating may include: square teeth or reflectors, trapezoidalteeth or reflectors, and/or curved grating arrangements.

Similarly, one or more of coupling regions 124 may include an opticalcoupling component. These optical coupling components may be used tooptically couple to optical components 118, for example, using opticalproximity communication. In some embodiments, such as when these opticalcomponents are disposed on the other substrate, optical coupling betweenoptical connector 110-1 and optical components 118 is mediated via pitsand spherical optical balls.

In additional to relaxing mechanical alignment tolerances, opticalconnector 110-1 may reduce geometric constraints in a variety ofcomponents. For example, widths of optical waveguides 122 may vary inoptical spreader component 114-1 and/or may be different than the widthsof other optical waveguides or than optical fibers 112. Thus, opticalwaveguides 122 may be wide (so-called fat waveguides) and/or may betapered, which allows wide optical fibers 112 to be optically coupled tosmaller devices, such as one or more sub-micron components in opticalcomponents 118.

Furthermore, note that optical spreader component 114-1 permitsreorganization of the spacing and positions of optical components 118and optical fibers 112. While a two-by-two array is used as anillustration, optical connector 110-1 supports a wide variety ofoptical-fiber array configurations and sizes. Furthermore, opticalspreader component 114-1 may facilitate optical coupling to opticalfibers 112 and optical components 118 on the same side of substrate116-1 or on opposite sides of substrate 116-1. If optical fibers 112 andoptical components 118 are on opposite sides of substrate 116-1, lightmay need to pass through substrate 116-1. This may be accomplished usinga transparent substrate and/or by etching holes through substrate 116-1,and inserting optical fibers in the holes (or fabricating opticalwaveguides in the holes).

In some embodiments, optical spreader component 114-1 is a passivedevice (e.g., it does not include an electronic device). For example,optical waveguides 122 may provide routing from coupling regions 120 tocoupling regions 124. However, in other embodiments optical spreadercomponent 114-1 includes active devices (e.g., it includes an electronicdevice).

In some embodiments, optical spreader component 114-1 includescomponents and/or functionality that facilitate processing and/orcommunication of optical signals, including: a wavelength-selectivemultiplexer, a wavelength-selective de-multiplexer, an optical switch,an optical filter, an optical add/drop, an optical monitor (which tapsand detects a portion of an optical signal), active optical amplitudeequalization (such as variable optical attenuation), and/or optical gain(such as all-optical, in-line gain).

In some embodiments, optical components 118 include another instance ofthe optical connector (disposed on another substrate), which facilitatesoptical coupling of sets of optical fibers (such as optical fibers 112).This is shown in FIG. 2A, which presents a block diagram illustratingoptical connectors 110-1 and 110-2. Coupling regions 124-1 through 124-4on optical connector 110-1 may optically couple to coupling regions124-5 through 124-8 on optical connector 110-2. This is shown in FIG.2B, which presents a block diagram illustrating overlap of opticalconnectors 110-1 and 110-2. As noted previously, in some embodimentsthis optical coupling is mediated using spherical optical balls, such asspherical ball 210 shown in FIG. 2C.

Referring back to FIG. 1A, because the coupling between optical fibers112 and optical spreader component 114-1 may be sensitive to mechanicalalignment, the mechanical and/or optical coupling between optical fibers112 and optical spreader component 114-1 may be rigid. For example,these components may be positioned relative to each other in a cleanenvironment under controlled conditions. (However, in other embodiments,the mechanical and/or optical coupling between optical fibers 112 andoptical spreader component 114-1 may be re-matable.)

Optical coupling between optical spreader component 114-1 and opticalcomponents 118 may be less sensitive to mechanical alignment.Consequently, optical spreader component 114-1 may be configured tore-matably mechanically and/or optically couple to optical components118. This may facilitate reconfiguring of a system in the field.Furthermore, a mechanical alignment tolerance of optical couplingbetween optical connector 110-1 and optical components 118 may be largerthan a carrier wavelength of one or more optical signals conveyed viaoptical fibers 112. Note that re-matable mechanical alignment mayutilize spherical balls and pits, and/or another alignment techniqueknown to one of skill in the art.

Re-matable coupling of optical connectors 110 (such as those shown inFIGS. 2A-2B) may offer lower cost and improved reliability in proximitycommunication. For example, it may allow active proximity-communicationcircuitry, optical-to-electrical and electrical-to-optical conversionelements, as well as the related power delivery and heat-removalcomplexity, to be reduced or eliminated by using optical spreadercomponent 114-1.

We now describe embodiments of a process for spatially segregatingoptical coupling between optical fibers 112 and optical component 114-1using optical connector 110-1. FIG. 3 presents a flow chart illustratinga process 300 for spatially segregating optical coupling between opticalfiber 112 (FIG. 1A) and at least one of optical components 118 (FIG. 1A)using optical connector 110-1 (FIG. 1A). During this method, a firstcoupling region in an optical spreader component in an optical connectorreceives an optical signal from an optical fiber (operation 310). Then,the first coupling region optically couples the optical signal to asecond coupling region in the optical spreader component via an opticalwaveguide in the optical spreader component (operation 312). Next, thesecond coupling region optically couples the optical signal to anoptical component (operation 314).

In some embodiments of process 300, there may be additional or feweroperations. Moreover, the order of the operations may be changed and/ortwo or more operations may be combined into a single operation.

In an exemplary embodiment, optical connector 110-1 (FIG. 1A) includessilicon-photonic channels, fiber-to-silicon couplers, andsilicon-to-silicon couplers. These silicon-to-silicon couplers may havea relaxed mechanical alignment tolerance relative to fiber-to-siliconand/or fiber-to-fiber couplers. Consequently, silicon-to-siliconcouplers may be used at the locations with the greatest need for arelaxed mechanical tolerance, such as field-matable connections ofoptical channels via a multi-fiber optical connector that has multiplerows and/or multiple columns.

Note that the improved cost, performance and reliability facilitated byoptical connectors 110 (FIGS. 1A-2B) may be useful in optical systemsthat include wavelength-division multiplexing (WDM), in which a numberof optical signals are multiplexed onto a given optical fiber. Forexample, optical connector 110-1 (FIG. 1A) may allow the aggregatenumber of channels in these optical systems to be increased (e.g., morecarrier wavelengths or more optical fibers 112 in FIG. 1A).

We now describe embodiments of a system, such as a computer system. FIG.4 presents a block diagram illustrating a computer system 400 thatincludes one or more integrated circuits 408 with one or more instancesof an optical connector, such as optical connector 110-1 (FIG. 1A).Computer system 400 includes: one or more processors (or processorcores) 410, a communication interface 412, a user interface 414, and oneor more signal lines 422 coupling these components together. Note thatthe one or more processors (or processor cores) 410 may support parallelprocessing and/or multi-threaded operation, the communication interface412 may have a persistent communication connection, and the one or moresignal lines 422 may constitute a communication bus. Moreover, the userinterface 414 may include: a display 416, a keyboard 418, and/or apointer 420, such as a mouse.

Memory 424 in the device 400 may include volatile memory and/ornon-volatile memory. More specifically, memory 424 may include: ROM,RAM, EPROM, EEPROM, flash, one or more smart cards, one or more magneticdisc storage devices, and/or one or more optical storage devices. Memory424 may store an operating system 426 that includes procedures (or a setof instructions) for handling various basic system services forperforming hardware-dependent tasks. Moreover, memory 424 may also storecommunications procedures (or a set of instructions) in a communicationmodule 428. These communication procedures may be used for communicatingwith one or more computers, devices and/or servers, including computers,devices and/or servers that are remotely located with respect to thedevice 400.

Memory 424 may also include one or more program modules 430 (or a set ofinstructions). Note that one or more of program modules 430 mayconstitute a computer-program mechanism. Instructions in the variousmodules in the memory 424 may be implemented in: a high-level procedurallanguage, an object-oriented programming language, and/or in an assemblyor machine language. The programming language may be compiled orinterpreted, i.e., configurable or configured, to be executed by the oneor more processors (or processor cores) 410.

Note that the one or more integrated circuits 408 (that include one ormore instances of an optical connector) may be included in a multi-chipmodule (MCM) (such as a switch or a processor). This MCM may include anarray of chip modules (CMs) or single-chip modules (SCMs), and a givenSCM may include at least one semiconductor die. Note that the MCM issometimes referred to as a ‘macro-chip.’ Furthermore, the semiconductordie may communicate with other semiconductor dies, CMs, SCMs, and/ordevices in the MCM using proximity communication of electromagneticallycoupled signals (which is referred to as ‘electromagnetic proximitycommunication’), such as capacitively coupled signals and/or proximitycommunication of optical signals (which are, respectively, referred toas ‘electrical proximity communication’ and ‘optical proximitycommunication’). In some embodiments, the electromagnetic proximitycommunication includes inductively coupled signals and/or conductivelycoupled signals.

Computer system 400 may include, but is not limited to: a server, alaptop computer, a personal computer, a work station, a mainframecomputer, a blade, an enterprise computer, a data center, aportable-computing device, a supercomputer, a network-attached-storage(NAS) system, a storage-area-network (SAN) system, and/or anotherelectronic computing device. For example, integrated circuit(s) 408 maybe included in a backplane that is coupled to multiple processor blades,or integrated circuit(s) 408 may couple different types of components(such as processors, memory, I/O devices, and/or peripheral devices).Thus, integrated circuit(s) 408 may perform the functions of: a switch,a hub, a bridge, and/or a router. Note that computer system 400 may beat one location or may be distributed over multiple, geographicallydispersed locations.

Optical connectors 110 (FIGS. 1A-2B) and/or computer system 400 mayinclude fewer components or additional components. Moreover, althoughthese devices and systems are illustrated as having a number of discreteitems, these embodiments are intended to be functional descriptions ofthe various features that may be present rather than structuralschematics of the embodiments described herein. Consequently, in theseembodiments, two or more components may be combined into a singlecomponent and/or a position of one or more components may be changed.Note that some or all of the functionality of the computer system 400may be implemented in one or more application-specific integratedcircuits (ASICs) and/or one or more digital signal processors (DSPs).Furthermore, functionality in optical connectors 110 (FIGS. 1A-2B)and/or computer system 400 may be implemented more in hardware and lessin software, or less in hardware and more in software, as is known inthe art.

The foregoing descriptions of embodiments of the present disclosure havebeen presented for purposes of illustration and description only. Theyare not intended to be exhaustive or to limit the present disclosure tothe forms disclosed. Accordingly, many modifications and variations willbe apparent to practitioners skilled in the art. Additionally, the abovedisclosure is not intended to limit the present disclosure. The scope ofthe present disclosure is defined by the appended claims.

1. An optical connector, comprising: an optical fiber; and an opticalspreader component, disposed on a substrate, configured to spatiallysegregate optical coupling between the optical fiber and an opticalcomponent, wherein the optical spreader component includes: a firstcoupling region that is optically coupled to the optical fiber; anoptical waveguide that is optically coupled to the first couplingregion; and a second coupling region that is optically coupled to theoptical waveguide, and which is configured to optically couple to theoptical component, wherein a location of the second coupling region isdifferent than a location of the first coupling region.
 2. The opticalconnector of claim 1, wherein the optical component includes an opticalsource.
 3. The optical connector of claim 1, wherein a mechanicalalignment tolerance of optical coupling between the optical connectorand the optical component is larger than a carrier wavelength of anoptical signal conveyed via the optical fiber.
 4. The optical connectorof claim 1, wherein the optical component includes an optical detector.5. The optical connector of claim 1, wherein the optical componentincludes another instance of the optical connector, which includesanother optical spreader component which is disposed on anothersubstrate.
 6. The optical connector of claim 5, wherein the secondcoupling region is optically coupled to a third coupling region in theother instance of the optical connector via optical proximitycommunication.
 7. The optical connector of claim 5, wherein the secondcoupling region is optically coupled to a third coupling region in theother instance of the optical connector via a spherical optical ball. 8.The optical connector of claim 1, wherein mechanical coupling betweenthe optical fiber and the optical spreader component is rigid.
 9. Theoptical connector of claim 1, wherein the optical spreader component isconfigured to re-matably mechanically couple to the optical component.10. The optical connector of claim 1, wherein the first coupling regionincludes an optical coupling component that optically couples an opticalsignal from the optical fiber to the optical waveguide.
 11. The opticalconnector of claim 10, wherein the optical coupling component includes adiffraction grating.
 12. The optical connector of claim 1, wherein theoptical spreader component is a passive device.
 13. The opticalconnector of claim 1, wherein the optical spreader component includesrouting from a first group of coupling regions, which includes the firstcoupling region, to second group of coupling regions, which includes thesecond coupling region.
 14. The optical connector of claim 1, whereinthe optical spreader component includes one of: a wavelength-selectivemultiplexer and a wavelength-selective de-multiplexer.
 15. The opticalconnector of claim 1, wherein the optical spreader component includesoptical switching of optical signals.
 16. The optical connector of claim1, wherein the optical spreader component includes an optical monitor.17. The optical connector of claim 1, wherein the optical spreadercomponent includes active optical amplitude equalization.
 18. Theoptical connector of claim 1, wherein the optical spreader componentincludes optical gain.
 19. A system, comprising: an optical connector,wherein the optical connector includes: an optical fiber; and an opticalspreader component, disposed on a substrate, configured to spatiallysegregate optical coupling between the optical fiber and an opticalcomponent, wherein the optical spreader component includes: a firstcoupling region that is optically coupled to the optical fiber; anoptical waveguide that is optically coupled to the first couplingregion; and a second coupling region that is optically coupled to theoptical waveguide, and which is configured to optically couple to theoptical component, wherein a location of the second coupling region isdifferent than a location of the first coupling region.
 20. A method forspatially segregating optical coupling between an optical fiber and anoptical component using an optical connector, comprising: receiving anoptical signal from the optical fiber at a first coupling region in anoptical spreader component in the optical connector, wherein the opticalspreader component is disposed on a substrate; optically coupling theoptical signal from the first coupling region to a second couplingregion in the optical spreader component via an optical waveguide in theoptical spreader component; and optically coupling the optical signalfrom the second coupling region to the optical component.